1. Field of the Invention
The present invention relates to an electric actuator, which is capable of moving a displaceable body by communicating a driving force of a drive unit to the displaceable body via a screw shaft.
2. Description of the Related Art
Heretofore, as a means for transporting workpieces or the like, an electric actuator has widely been used for displacing a slider that transports a workpiece, in which a feed screw is driven rotatably by a rotary drive force of a rotary drive source such as a motor or the like. Such an electric actuator, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2004-156636, comprises a body, a ball screw disposed rotatably in the interior of the body, a nut, which is screw-engaged via balls with the ball screw, and a displaceable body, which is connected to the nut. The nut is displaced together with the displaceable body along an axial direction by rotating the ball screw under a driving action of the electric motor.
In the case that the aforementioned electric actuator is used in a clean room, for example, for performing semiconductor manufacturing, since dust, debris or the like tends to be generated due to frictional wear of the ball screw, the balls, and the nut, which are enmeshed mutually with each other, there is a need to prevent such dust or the like from being discharged to the exterior.
For example, as a dust collecting structure for preventing dust or the like from being discharged to the exterior, as disclosed in Japanese Laid-Open Patent Publication No. 05-016092, an electric actuator is known having a ball screw accommodated in the interior of a casing, and a dust collecting pipe in which plural suction holes are formed, and which is disposed in the vicinity of a slit that opens on an upper portion of the casing. By supplying a negative pressure fluid to the dust collecting pipe, dust or the like from the interior of the casing is aspirated through the suction holes.